malware – What is "Waiting for eb2.3lift.com …."?

I'm using purevpn on Firefox, I've noticed that sometimes when I open the browser, it hangs and, in the lower left corner, it says "Waiting for eb2.3lift.com … "

I've tried google this eb2.3lift.com but did not seem to find any answers. Does anyone know if there is a malware / virus?

P.S. I have installed the free AVG version, I have performed a system scan and found nothing.